In the past there have been various vehicle barriers placed directly across roadways to prevent vehicle penetration. One of the difficulties associated with such barriers is that the barrier must be removably placeable across a roadway. Thus, the barrier must be massive enough to arrest a vehicle, yet light enough to be removed for regular vehicular traffic.
In contradistinction to the above methods of arresting a vehicle, as discussed in Pat. Application Ser. No. 310,735 filed Feb. 13, 1989, now Pat. No. 4,923,327, by Alexander Gorlov incorporated herein by reference, a vehicle is deflected from its direction of travel through the utilization of a turnstile, which is moveable into the roadway to deflect the vehicle into a crash barrier to the side of the driveway. The turnstile/cam in one embodiment, includes a sector of a spoked wheel having as a central hub a freely rotatable cylindrical section, with the hub spokes projecting out beyond the sector to engage the vehicle as it comes into contact with the sector. When such occurs the sector continues to rotate in the direction down the driveway to present increasing portions of the sector to the vehicle and further deflect the vehicle off the roadway.
The turnstile is normally at a rest position, with the sector being completely removed from the driveway. Upon impending impact of an unauthorized vehicle, means are provided to rotate the sector at least partially into the driveway where it is hit by at least a portion of the vehicle coming through the entrance to the driveway. Here the kinetic energy of the vehicle further swings the rotatable sector towards the center of the driveway for assured vehicle deflection. This turnstile therefore redirects the initial vehicular motion along the direction of the driveway and causes the vehicle to be cammed into a different direction, that being in the direction of an immovable crash-barrier. Preferably the vehicle comes to rest straddling the driveway to prevent further unauthorized traffic from coming through the gateway.
The aforementioned terrorist vehicle-arresting system thus includes a crash barrier positioned at one side of a driveway and a turnstile having a circular sector positioned at the other side of the driveway in such a manner that upon entrance of an unauthorized vehicle through a corresponding gate across the entrance of the driveway, means are provided to rotate the turnstile such that the turnstile deflects the vehicle into the crash barrier.
Having described the basic operation of a system for deflecting terrorist vehicles into a crash barrier utilizing a turnstile/cam, it will be appreciated that in view of the impulse delivered by the truck to the turnstile and in view of the fact that all tires are in firm frictional contact with the pavement, the turnstile of necessity needs to be somewhat massive, both as to the sector itself and as to the hub and bearing assembly associated with the sector. Moreover, the radial spokes need to be sufficient strength so as not to crumple or deform upon impact of the vehicle with the sector.
Thus, in order to ensure that the vehicle is in fact deflected, it is necessary that all mechanical components of the system be of sufficient strength to, for instance, deflect a 12 ton truck impacting the deflection system at greater than 45 miles per hour.